OBJECTIVES: (1) To continue follow-up of patients with cerebral vascular insufficiency (transient ischemic attacks) and other forms of stroke using our Stroke Registry, (2) To initiate intervention studies, to take cohorts from the pool of patients in our registry and to initiate new treatments such as: a. Use of pentobarbitol in evolving cerebral infarction and b. warfarin in patients with transient ischemic attacks, (3) To continue the assessment of new screening techniques for extracranial vascular disease particularly carotid artery scanning with Doppler ultrasonic techniques and regional cerebral blood flow studies using the xenon inhalation method, (4) To continue the neuropsychological investigations of patients with cerebral circulatory disozders and to correlate these findings with regional blood flow studies, (5) To assess risk factors for stroke, (6) To improve the laboratory animal model for cerebral circulatory disorders by: a. Gerbil studies which will include selective breeding, b. Primate models who are fed experimental diets to produce a natural cerebral atherosclerotic model, c. Physiological investigations on primates who have experimental occlusion of posterior and/or middle cerebral arteries. (7) Initiate studies on the behavioral consequences of stroke both in animal models and in human beings involving sociological investigation techniques.